Like he never left: Spurs guard Ray McCallum walked into Sleep Train Arena for Thursday morning’s shootaround and experienced an acute feeling of been-there, done that.

“It literally feels like I was just here,” McCallum said.

Obtained in a July 9 trade with the Kings, McCallum made his Spurs debut in the same arena he called home for his first two NBA seasons.

Lost in the backcourt shuffle in Sacramento, McCallum was working out in Los Angeles when he learned of the trade.

“I had heard for a week or so that it might happen, but I didn’t think it would,” said McCallum, who can see his old house from the freeway leading to the Kings’ arena. “When it did, I was excited. It’s a great opportunity for me.”

Karl, who coached McCallum last season, said he thinks the 24-year-old will settle into a combo guard role off the bench for the Spurs.

Popovich is looking at options to replace both a point guard (Cory Joseph) and a shooting guard (Marco Belinelli) on the Spurs’ bench.

McCallum shook off a rough start to finish Thursday’s game with eight points.

“I personally think his scoring skills are a little higher level than his point-guard skills,” Karl said. “But I think San Antonio will figure out how to use him.”

Benvenuto, Messina: With Popovich sitting out Thursday’s preseason opener - hanging back in San Antonio with Tim Duncan, Tony Parker, Manu Ginobili and Boris Diaw - the Spurs handed the reins to lead assistant Ettore Messina.

It marked the third time Messina has covered for Popovich since joining the team last season, and the second time in the preseason.

“You feel the responsibility, but this is a machine that works on its own,” said Messina, a coaching icon in European basketball circles. “You just try to get in and don’t mess it up.”